OSX 10.9 (mavericks), maven is not installed by default. So, here's how to do that.
If you haven't install homebrew, install that first unsing the following command:
ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go/install)"
Then, install Maven.
brew install maven
Type the below command to verify that Maven is installed successfully.